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Chemical pollution is one of the main contributors to the degradation of lotic ecosystems and their biodiversity. Among chemicals driving lotic biodiversity decline are anthropogenic organic micropollutants (AOM), which affect the survival and functioning of freshwater organisms. Continuous exposure of freshwater organisms to AOM leads to adverse effects that sometimes cannot be traced with standard toxicity methods such as standard toxicity testing or biodiversity indices. Among these effects of AOM are selective or mutagenic effects that cause impaired species genetic diversity. Thus, the correlation between different levels of AOM and genetic diversity of species is still poorly understood. However, it can be explored by applying population genetics screening.
In Chapter 1 of this thesis, background information on environmental pollution, genetic screening, and the detection of evolutionary-relevant AOM effects in freshwater organisms are described and the thesis goals are identified. The main goal of the thesis is to study whether AOM exposure occurring in European rivers causes a significant evolutionary footprint in freshwater species and leads to a selection of more tolerant geno-and phenotypes. Therefore, population genetics indices together with high-resolution chemical exposure screening of a widespread indicator invertebrate species, Gammarus pulex (Linnaeus, 1758), living in polluted and pristine European rivers were investigated.
In Chapter 2, the development of a genetic screening method for G. pulex (microsatellites) is described. Due to genetic differentiation and the presence of morphologically cryptic lineages, the available sets of target loci do not enable a reliable population genetic characterization of G. pulex from central Germany. Thus, a novel set of microsatellite loci for a high-precision assessment of population genetic diversity was here applied. Eleven loci were first identified and thereafter amplified in G. pulex from three rivers. The new loci reliably amplified and indicated polymorphisms in the studied amphipods. The amplification resulted in the successful identification of genetically distinct populations of G. pulex from the analyzed rivers. Moreover, the microsatellite loci were amplified in other genetic lineages of G. pulex and another Gammarus species, G. fossarum, promising a broader applicability of the loci in related amphipod species.
In Chapter 3, the effects of AOM on species genetic differentiation and sensitivity to toxic chemicals in a typical central European river with pristine and AOM-polluted sections was investigated. The river’s site-specific concentrations of AOM were assessed by chemical analysis of G. pulex tissue and water samples. To test, whether different levels of AOM in the river select for pollution-dependent genotypes, the genetic structure of G. pulex from the river was analyzed. Finally, the toxicokinetics of and sensitivity to the commonly used insecticide imidacloprid were determined for amphipods sampled at pristine and polluted sections to assess whether various levels of AOM in the river influence sensitivity of G. pulex to imidacloprid. The results indicated that different levels of AOM did not drive genetic divergence of G. pulex within the river but led to an increased sensitivity of exposed amphipods to imidacloprid. The amphipods living in polluted river sections were more sensitive to the insecticide due to chronic exposure to toxic levels of AOM.
In Chapter 4, the relationship between site-specific pollution levels of AOM and genetic diversity parameters of G. pulex was analyzed at the regional scale within six rivers in central Germany. The genetic structure of G. pulex in the studied area was tested for relatedness to the waterway distance between sites. Gammarus pulex genetic diversity parameters, including allelic richness and inbreeding rate, were tested against environmental pollution parameters using linear mixed-effect- and structural-equation models. According to the results, G. pulex genetic diversity parameters were significantly associated with the detected AOM levels. At sites with high concentrations of AOM and toxicity potential G. pulex showed reduced genetic diversity and increased rates of inbreeding. These results suggest that AOM play a major role in shaping the genetic diversity of G. pulex in rivers.
According to the findings presented here, the applied microsatellites can be used to successfully detect changes in genetic patterns in freshwater amphipods facing increased levels of AOM. The findings indicate that levels of AOM representative for European rivers do not lead to the separation of genotypes among G. pulex as the connectivity between sites majorly contributes to species’ genetic structure. However, the chronic exposure to increased levels of toxic AOM leads to a reduction of species genetic diversity and increases the sensitivity of G. pulex to the toxic chemical effects.
Background and purpose: Transient splenial oedema, also known as reversible splenial lesion syndrome (RESLES), is a rare magnetic resonance imaging (MRI) finding that presents as a round or ovoid focal oedema in the posterior corpus callosum, and is associated with a wide range of clinical conditions. The aetiology of RESLES is not fully clear. We aimed to investigate conflicting pathophysiological hypotheses by measuring local glucose metabolism in patients with RESLES.
Methods: We retrospectively analysed patients with RESLES after reductions in antiseizure medications during in-hospital video electroencephalography monitoring. We measured local glucose uptake using positron emission tomography/computed tomography and compared matched cohorts of patients with and without MRI evidence of RESLES using nonparametric tests.
Results: Local glucose metabolism in the splenium of seven patients with RESLES was not significantly different from the glucose metabolism of the seven patients in the matched cohort. This was true using both regular and normalized standardized glucose uptake value calculation methods (p = 0.902 and p = 0.535, respectively).
Conclusion: We found no evidence of local glucose hypometabolism in RESLES, which supports previous pathophysiological considerations that suggest that RESLES is an intercellular, intramyelinic oedema rather than a typical intracellular cytotoxic oedema, which is not reversible.
Academic self-efficacy (ASE) refers to a student’s global belief in his/her ability to master the various academic challenges at university and is an essential antecedent of wellbeing and performance. The five-item General Academic Self-Efficacy Scale (GASE) showed promise as a short and concise measure for overall ASE. However, of its validity and reliability outside of Scandinavia is limited. Therefore, this paper aimed to investigate the psychometric properties, longitudinal invariance, and criterion validity of the GASE within a sample of university students (Time 1: n = 1056 & Time 2: n = 592) in the USA and Western Europe. The results showed that a unidimensional factorial model of overall ASE fitted the data well was reliable and invariant across time. Further, criterion validity was established by finding a positive relationship with task performance at different time stamps. Therefore, the GASE can be used as a valid and reliable measure for general ASE.
Despite its popularity in practice, the Grit-O Scale has shown inconsistent factorial structures and differing levels of internal consistency in samples outside the USA. The validity of the Grit-O Scale in different contexts is, therefore, questionable. As such, the purpose of this paper was to determine whether the Grit-O Scale could be used as a valid and reliable measure to compare grit across different nations. Specifically, the aim was to investigate the factorial validity, reliability, and concurrent validity of the Grit-O Scale and to investigate measurement invariance across three national cohorts (Europe, the USA, and Hong Kong). Data were gathered from 1888 respondents stemming from one USA- (n = 471), two Hong Kong- (n = 361) and four European (n = 1056) universities. A series of traditional CFA and less restrictive ESEM models were estimated and systematically compared to determine the best factorial form of the Grit-O Scale. The results showed that a bifactor ESEM model, with one general factor of overall grit and two specific factors (consistency of interest and perseverance of effort), fitted the data best, showed strong measurement invariance across the three samples, and showed itself to be a reliable measure. Furthermore, concurrent validity was established by showing that the three grit factors were directly and positively related to task performance. Meaningful latent comparisons between the three cultural cohorts could therefore be made. The results imply that cross-national comparisons of grit may only be problematic when traditional CFA approaches are favoured. In contrast, ESEM modelling approaches may compensate for cross-national differences in understanding grit and control for differences in the interpretation of the scale’s items. Therefore, the bifactor ESEM approach may be more appropriate for cross-cultural and cross-national comparison studies, as it allows for these differences to be meaningfully captured, modelled, and controlled for.
We aimed to evaluate the factors associated with hemorrhage (HA) of melanoma brain metastases (MBM) after Cyberknife stereotactic radiosurgery (SRS) in the modern era of systemic therapy. A total of 55 patients with 279 MBM were treated in 93 fractions. The median age, SRS dose, radiological follow-up, and time to HA were 60.4 years, 20 Gy, 17.7 months, and 10.7 months, respectively. Radiologically evident HA was documented in 47 (16.8%) metastases. Of the 55 patients, 25 (45.4%) suffered an HA. Among those, HA caused grade 3 toxicity in 10 patients (40%) and grade 1 symptoms in 5 patients (20%). Ten patients (40%) with HA experienced no toxicity. Logistic regression revealed the use of anticoagulants and the administration of systemic therapy within 7/15 days from SRS to be predictive for HA. When considering the HA causing grade 3 symptomatology, only the use of anticoagulants was significant, with the delivery of whole brain radiation therapy (WBRT) before the HA narrowly missing statistical significance. Our retrospective analysis showed that the administration of modern systemic therapy within 7/15 days from SRS may contribute to HA of MBM, though it appears safe, at least concerning grade 3 toxicity. The use of anticoagulants by the time of SRS significantly increased the risk of HA.
Background: The aim of this study was to identify pre-operative parameters able to predict length of stay (LoS) based on clinical data and patient-reported outcome measures (PROMs) from a scorecard database in patients with significant aortic stenosis who underwent TAVI (transfemoral aortic valve implantation). Methods: 302 participants (51.7% males, age range 78.2–84.2 years.) were prospectively recruited. After computing the median LoS value (=6 days, range = 5–8 days), we implemented a decision tree algorithm by setting dichotomized values at median LoS as the dependent variable and assessed baseline clinical variables and PROMs (Clinical Frailty Scale (CFS), EuroQol-5 Dimension-5 Levels (EQ-5D) and Kansas City Cardiomyopathy Questionnaire (KCCQ)) as potential predictors. Results: Among clinical parameters, only peripheral arterial disease (p = 0.029, HR = 1.826) and glomerular filtration rate (GFR, cut-off < 33 mL/min/1.73 m2, p = 0.003, HR = 2.252) were predictive of LoS. Additionally, two PROMs (CFS; cut-off = 3, p < 0.001, HR = 1.324 and KCCQ; cut-off = 30, p = 0.003, HR = 2.274) were strong predictors. Further, a risk score for LoS (RS_LoS) was calculated based on these predictors. Patients with RS_LoS = 0 had a median LoS of 5 days; patients RS_LoS ≥ 3 had a median LoS of 8 days. Conclusions: based on the pre-operative values of the above four predictors, a personalized prediction of LoS after TAVI can be achieved.